Exchange traded fund investors plowed into equity ETFs last week as the stock market rallied, according to the latest flow data.

ETFs took in $2.3 billion last week, according to EPFR Global data, the Financial Times reports.

“While it has been a volatile year, we have certainly seen an almost surprising willingness for people to jump back,” said Cameron Brandt, head of research at EPFR, in the report. “The vehicle for that has increasingly been ETFs, which allow investors [mostly institutions]to move quickly.”

“We’ve noticed this lag effect before. ETF investors tend to react quicker to news, whereas it can take mutual fund investors longer to move in and out of funds,” added Tom Roseen, a senior analyst with Lipper.